The 29th season of CBS’ Survivor has begun filming in Nicaragua, and host Jeff Probst says that two contestants left the show 48 hours before the competition began for medical reasons.

“We just lost two contestants [Friday],” Probst tells EW’s Dalton Ross, who’s hosting EW Morning Live with Jessica Shaw from the set of Survivor: San Juan del Sur – Blood vs. Water all week on Entertainment Weekly Radio. “We came out here with 20. We spend months casting our show – months. I mean, this is like….who you’re gonna ask to prom. All year you’re like, ‘Is it her or her?’ and ‘Will she say yes?’ And you finally get your 20 people, and then through no fault of their own – just a medical situation – they can’t play…. So instead of 20, it puts us at 18. Instead of equal men and women, it puts us uneven men and women.”

Listen to Probst explain why the show must go on in the clip below. Bonus: You’ll also hear a Survivor helicopter pass overhead.